Ratio changing lever mechanism



Feb. 20, 1940. w. F. BOLDT RATIO CHANGING LEVER MECHANISM Filed Dec. 5,1938 2 She ets-Sheet 1 INVENTOR W.F. BOLDT ATTO Feb. 20, 1940.

W. F. BDLDT RATIO CHANGING LEVER MECHANISM Filed Dec. 5, 1938 2Sheets-Sheet 2 FIGZ.

FIGS

INVENTOR.-

Patented Feb. 20, 1940 UNITED STATES PATENT OFFICE RATIO CHANGING LEVERMECHANISM a corporation of Delaware Application December 5, 1938, SerialNo. 243,910

11 Claims.

My invention relates to levers and more particularly to levers which areprovided with means for changing the leverage ratio thereof.

One of the objects of my invention is to produce an improved levermechanism which will permit the leverage ratio thereof to beautomatically changed from one ratio to a higher ratio when the forcenecessary to move the member being actuated reaches a predeterminedvalue.

,Another object of my invention is to provide means for holding thelever mechanism in any position it may assume and to also permit thelever mechanism to be readily released when desired.

Other objects of my invention will become apparent from the followingdescription taken in connection with the accompanying drawings in whichFigure 1 is a view showing my improved lever mechanism in .inoperativeposition; and Figures 2 and 3 are views showing the leverage mechanismin two operative positions.

Referring to the drawings in detail, numeral I indicates the main leverwhich is pivotally 26 mounted upon a shaft 2 fixed to some suitablesupport. The lower arm 3 of this lever has associated therewith anauxiliary lever 4 pivotally mounted at its upper end to said arm by apin 5 and also pivotally mounted at its intermediate portion by means ofa pin 6 to a pull-rod 1 connected to the mechanism to be actuated. Thelower end of the auxiliary lever 4 has pivotally mounted thereon a pawl8 which is adapted to cooperate with the teeth 9 on a fixed plate ID.The auxiliary lever carries a' leaf spring II for normally biasing thepawl 8 toward engagement with the teeth 9.

The pull-rod 1 extends to a point beyond the arm 3 and auxiliary lever 4and mounted on itsend is an abutment member I2 for cooperation with oneend of a compression spring I3 positioned on the pull-rod. The inner endof the spring has associated therewith an abutment sleeve I4 slidablymounted upon the pull-rod and forming an abutment surface for engagementby the arm 3 of the main lever I. V

The lower end I5 of arm 3 is so constructed as to cooperate with thetail I6 of pawl 8 and when said end is in the position shown in Figurel, the pawl will be held in inoperative position. The lower end portionI5 carries a detent I! which is slidably mounted in a suitable socket I8and prevented from turning thereon by means of a pin I9 cooperating witha slot 20. The detent- I1 is along side the main lever I to a pointadjacent the top of the upper arm 22 of said lever. This rod iscontrolled by a plunger 23 slidably mounted in the hollow end of themain lever, the-lower end 01 said plunger cooperating with a short lever24 l which is pivoted on the main lever and connected to the upper endof rod 2|. A spring 25 biases the detent Il toward a position where itengages the teeth 9 on plate I0 but, as shown in Figure 1, thisengagement is prevented when the parts are in inoperative position dueto the beveled surface 26 (Figure 3) oithe detent engaging with the tailI6 of pawl 8. I

When the parts are in the position shown in Figure 1, the pull-rod Iwill be in its inoperative position and the mechanism which is beingactuated will be released. If it is now desired to operate the pull-rod,the upper end of arm 22 of the main lever is grasped by the hand of theoperator and the lever rotated in a clockwise di- 20 rection, asindicated by the arrow A.. The pull- Y rod 1 will be actuated throughthe spring I3 by means of the lower arm 3. The auxiliary lever 4 will becarried with arm 3 of the main lever I and their relative positions willnot be changed. 8 The positions of the parts as the lever I is initiallymoved to operate the pull-rod are as shown in Figure 2.

When the force necessary to move the pull-rod reaches a predeterminedvalue, which is determined by-spring I3, the spring will begin to becompressed. This compression of the spring will result in arm 3 of themain lever being moved away from the auxiliary lever 4. When thisrelative movement between the two levers is sufficient, pawl 8 will beforced into engagement with one of the teeth 9 by the action of leafspring II and the lower end of the auxiliary lever will now be heldstationary. The relative movement between the lower arm 3 and theauxiliary lever 4 also permits spring 25 to move detent I1 so that itcan engage one of the teeth 9 on plate I0.

Continued movement of lever I in the direction of arrow A will nowresult in additional compression of spring I3 and the swinging of theauxiliary lever 4 about its lower end due to the pivotal connection ofarm 3 with the auxiliary lever 4 by means of pin 5. The pull-rod,instead of being actuated directly by the main lever, will 50 now beactuated through the auxiliary lever 4, thus increasing the leverageratio. When the pull-rod has been moved sufficiently, it will be held inthe desired position by means of the detent I1. The position which theparts assume after the pull-rod has been operated to the desiredposition is shown in Figure 3.

When it is desired to release the pull-rod, the operator need only pressdownwardly on the plunger 23 at the top of the main lever, thus causingthe detent I! to be disengaged from the cooperating tooth 9. This willnow permit the lower arm 3 oi. the lever to move in a counter- 1clockwise direction and to a position where the lower end of arm .8 willengage the tail I6 of pawl 8, thereby forcing the pawl out of engagementwith its cooperating tooth 9. The lever I and the auxiliary lever i willnow assume their inoperative positions as shown in Figure 1.

It is apparent from the above description that the lever mechanismpermits the leverage ratio at which the pull-rod is being actuated to bematerially increased and at a time when the force necessary to operatethe pull-rod is a predetermined value. In the particular constructionshown the leverage ratio after the change-over has taken place isapproximately two and one-half times the previous leverage.

My improved mechanism has been found to be very useful in applyingbrakes. When my leverage mechanism is used to actuate the frictionelement, said element will be brought into engagement with the drum bythe first movement of lever l and at the low leverage ratio which is thedesired operation. The change-over to the high leverage ratio willautomatically takeplace as soon as the greater force is neoessary'to apply pressure to the friction element and force 'it into brakingengagement with the drum; Re-

gardless of the distance that the pull-rod I must be operated to bringthe friction element into engagement with the drum, the change inleverageratio will automatically take place at the proper time. It isthus seen that the wear of the friction element will have no efiect inchanging the time of the leverage ratio change-oven Being aware of thepossibility of modifications in the particular structure hereindescribed without departing from the fundamental principles of myinvention, I do not intend that its scope be limited except as set forthby the appended claims.

Having fully-described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. .In a lever mechanism, a support, a main lever pivoted on the supportand adapted to be actuated by a force applied directlythereto, an

v auxiliary, lever connected to-the-main lever, an

actuatable member connected to the auxiliary lever, a yieldable memberfor operatively connecting the main lever and member, and ratchet meansfor establishing a fixed fulcrum for'the auxiliary lever about which theauxiliary lever is rotated by movement of the main lever when saidyieldable member yields and permits relative'movement between thelevers.

2. In a lever'mechanism, a support, a main lever pivoted on the support,an auxiliarylever pivotedon the main lever, an actuatable memberconnected to the auxiliary lever at a point spaced from the pivotalconnection with the'main lever, means for causing the levers'to move asa unitary structure to operate the member when the required actuatingforce to move said member is less than a predetermined value, said meansembodying means for permitting the main lever to move relatively to theauxiliary lever'when said force is greater than the predetermined value.

and means for causing said main lever when ate the member when therequired actuating force to move said member is less thana predeterminedvalue, said means embodying means for permitting the main lever to moverelatively to the auxiliary lever when said force is greater than thepredetermined value, and means for causing said main lever whenmoved'relatively to the auxiliary lever to operate the member throughthe auxiliary lever, said last named means embodying means forestablishing a fulcrum for the other end of the auxiliary lever.

4. In a lever mechanism, a support, a main lever pivoted on the support,an auxiliary lever pivoted on the main lever, an actuatable memberconnected to the auxiliary lever, means for causing the levers to moveas a unitary structure to operate the member when the required actuatingforce to move said member is less than a predetermined value, said meansembodying means for permitting the main lever to move relatively to theauxiliary lever when said force is greater than thepredeterminedfvalue,and means comprising. a pawl carried by the auxiliary lever and 1 acooperating. fixed toothed member forestablishing a fulcrum for saidauxiliary lever wherebyjthemainlever can operate the actuatable memberthrough the auxiliary lever when said main lever is permitted tomove'relatively to the auxiliary lever.

5. In a lever mechanism, a support, a main "lever pivoted on thesupport,an auxiliary lever greater than the predetermined value, meanscomprising a pawl carried by the auxiliary lever and 'a cooperatingfixed toothed member for establishing a fulcrum for said auxiliary leverw'hereby'the main lever can operate the actuatable member through theauxiliary lever when said main lever is permitted to move relatively tothe auxiliary lever, andineans for automatically releasingjsaid'pawlfromthe toothed member by the main lever when it is permitted to returnto the position it had prior to its relative movement withrespect totheauxiliary lever.

6. In a lever mechanism, a support, a main lever pivoted on the support,an auxiliary lever pivoted on the main lever, an actuatable memberconnected to the auxiliary lever, means i'orcausing the levers to moveasa unitary structure to operate the member when the'required actuatingforce to move said member is less than a predetermined value, said meansembodying means for permitting the main lever to move relatively to theauxiliary lever when said force is greater than the predetermined value,means for cans-' with the main lever and with the member. and

releasable means for maintaining the levers in their operativepositions. I

'7. In a lever mechanism, a support, a main lever pivoted on thesupport, an auxiliary lever pivoted on the main lever, an actuatablemember connected to the auxiliary lever, a spring connecting the memberto the main lever, said spring permitting the main lever to operate themember without relative movement between the levers when the forcenecessary to move the member is less than a predetermined value and topermit relative movement between the levers when said force is oi. agreater value, and means operable by the relative movement of the leversfor establishing a fixed fulcrum for said auxiliary lever and permittingsaid main lever to operate the member through the auxiliary lever.

B. In a lever mechanism, a support, a main lever pivoted on thesupport,an auxiliary lever pivoted on the main lever, an actuatablemember connected to the auxiliary lever, a spring connecting the memberto the main lever, said spring permitting the main) lever to operate themember without relative movement between the levers when the forcenecessary to move the member is less than a predetermined value and topermit relative movement between the levers when said force is 01' agreater value, a pawl caried by the other end of the auxiliary lever, afixed toothed member, and means operable by the relative movement of thelevers for permitting the pawl to engage the toothed member andestablish a fulcrum forthe auxiliary lever whereby the main lever canoperate the member through the aux- Jorce is or a greater value, a pawlcarried by the other end of the auxiliary lever, a fixed toothed member,means normally causing said pa l to be inoperative and operable by therelativ move-- ment of the levers for permitting the pawl to en-,

gage the toothed member and establish a fulcrum for the auxiliary leverwhereby themain lever canoperate the member through said auxiliarylever, and releasable means for maintaining v the levers in theiroperative positions.

. l0. In a lever mechanism, a support, a main lever pivoted on thesupport, an auxiliary lever pivoted at one end on the main lever,'anactuatable member connected to a pull-rod pivoted to an intermediateportion of the auxiliary lever, a compression spring carriedbythepull-rod and interposed between the pull-rod and the main lever, saidspring permitting them'ainjl'ever to operate the pull-rod withoutrelative movement between the levers when the force necessary to movethe pull-rod is less than a predetermined value and to permit relativemovement between the levers when said force is of a greater value. andmeans operable by the relativemov'ement of the levers for establishingafixed fulcrum for the other end of the auxiliary lever and permit-iting said main lever to operate the pull rod' through the auxiliarylever.. t i V 11. In a lever mechanism, a support,v a main.

lever pivoted on the support, an auxiliary lever pivoted at one end'onthe main lever, anactuatable member connected to a pull-rodpivoted to anintermediate portion of the auxiliary lever, a compression springcarried by the pull-rod and interposed between the pull-rod and the'main lever, said spring permitting the main leverto" operate thepull-rod without relative movement between the levers when, theforce'h'ecessary to move the pull-rodisle'ss than a predetermined valueand to permit relative movement between the levers when said force is ofa greater value, a pawl on the other end of the auxiliary lever, atoothed member for cooperating with the pawl, cooperating meanscarried'by the pawl and the main lever for permitting said pawl toengage the toothed member when the levers'move relatively to each other,and manually controlled detent means-carried by the mainlever andcooperating with the toothed member for holding the levers in operativepositions.

WERNER F. BOLDT.

